1. Field of the Invention
The present invention relates to a display device, and in particular, to a non-light-emitting display device such as a liquid crystal display device.
2. Description of Related Art
Recently, for example, liquid crystal display devices have been used widely in liquid crystal televisions, monitors, and mobile telephones, as flat panel displays having features such as thinness and light weight, compared with conventional Braun tubes. Such a liquid crystal display device includes a backlight device emitting light and a liquid crystal panel displaying a desired image by playing a role of a shutter with respect to light from light sources provided in the backlight device.
Further, in the above-described conventional liquid crystal display device, for example, JP 2006-220685 A has proposed the following: with respect to a liquid crystal panel not provided with color filters, a driving method (so-called field sequential driving) is performed in which LEDs of three colors of RGB are used as light sources and they are caused to blink sequentially, so that an image of red alone, an image of green alone, and an image of blue alone are displayed in order in one frame period. Thus, this conventional liquid crystal display device enables a high pixel density display and low power consumption of the liquid crystal panel.
Specifically, in the above-described conventional liquid crystal display device, as shown in FIG. 9, in any five pixels a, b, c, d and e for example, LEDs of RGB are switched on sequentially in a frame period of information to be displayed on the liquid crystal panel. More specifically, in the conventional liquid crystal display device, the LED of R is switched on between a time T51 and a time T53 in the frame period between the time T51 and a time T52. After that, in the conventional liquid crystal display device, the LED of G is switched on between a time T54 and a time T55, and the LED of B is switched on between a time T56 and a time T57. Further, at this time, in each of the pixels a-e, a source signal (voltage signal) in accordance with information to be displayed is supplied from a source driver (not shown). Thus, each of the pixels a-e is activated in accordance with the supplied source signal and outputs the corresponding color of light toward outside, whereby an image of said color is displayed. Specifically, in FIG. 9, a value indicated by % in each of the pixels a-e refers to a transmittance in the pixel. That is, in the case where the magnitude of the source signal at the time of displaying an information with the maximum luminance value is set as 100%, the value in each of the pixels a-e indicates the magnitude of the source signal to be supplied thereto in accordance with the information to be displayed. For example, in the pixel a, 80% of the source signal is given when the LED of R of is switched on at 100%, whereby the pixel a displays information of red with the luminance value of 80% based on the maximum luminance value. Further, the period between the time T53 and the time T54, the period between the time T55 and the time T56, and the period between the time T57 and the time T52 respectively are set as response times for writing source signals into the liquid crystal.
Further, in the conventional liquid crystal display device, as shown in FIG. 9, since one pixel displays colors of RGB sequentially, the high pixel density display of the liquid crystal panel is achieved. Further, in the conventional liquid crystal display device, since the number of source drivers to be installed is reduced by ⅓ as compared with the liquid crystal panel using color filters, low power consumption is achieved.
In the above-described liquid crystal display device, a technique for improving the moving image performance is required. Particularly, in a high-end product such as a liquid crystal television capable of receiving digital broadcasting or the like, there is a strong demand for realizing the moving image performance of the CRT level. Therefore, for changing the liquid crystal display device that is a hold-type display device into a (pseudo) impulse-driven type, a black insertion to a display screen is required.
However, in the conventional liquid crystal display device as described above, the black insertion is not taken into consideration, which prevents the improvement of the moving image performance.